Intermediates to carbocyclic nucleosides

Abstract

The present invention relates to certain purine nucleoside analogues containing a carbocyclic ring ill place of trip sugar residue, salts, esters and pharmaceutically acceptable derivatives thereof, processes for there preparation, pharmaceutical formulations containing them, and to the use of such compounds in therapy, particularly the treatment of or prophylaxis of certain viral infections.

We claim: 
     
       1. A process for the preparation of a compound of formula (VIIIb), wherein X represents an anion, its mirror ##STR11## image enantiomer or a mixture of such enantiomers which comprises reacting (-)-2-azabicyclo 2.2.1!hept-5-ene-3-one of formula (IX), its mirror image enantiomer or a mixture of such enantiomers ##STR12## with one or more equivalents of an acid and one or more equivalents of water. 
     
     
       2. A process as claimed in claim 1 wherein the said acid has a pKa of less than two.